Assuming your TV has a spare HDMI port, I second the recommendation for a HomeWorX HW-180STB-Y18 (Mediasonic is the company that imports these). Or an iView 3200STB, which is very similar (Wiltronic Corp. imports these). They will do basic recordings with a USB-attached drive. Some thumb drives will work but many won't; a real HDD (up to 2 TB) is best. They're no TiVo, but if you just want basic VCR-style recordings, they'll work fine.
You needn't worry about picture quality. It's all digital now; as long as your signal isn't so weak or noisy that it pixelates and/or drops out completely, your picture will be exactly as it was transmitted.
You should know that the highest sound quality you'll get over the air is 5.1, no matter which tuner you buy. That will probably improve when ATSC 3.0 comes around, but you'll need a new tuner then anyhow.